the crossmember mounts to the frame which it sleeved with 1/4 wall squaretube and 4 1/2inch grade 8 bolts down each side. just for added protection i will tie the crossmember into the fram at the back of the skid. The radius arms are 1.5in dom .25 wall sleved with 1.75in dom .120 wall which makes them just over 3/8 on an inch thich those bends bent the pins in my model4 bender i dont think i will have a problem there. the picture ,ake the bends look larger than they are as well. thanks for your input